1. Field of the Invention
The present invention relates generally to pressure gauges and more particularly to an improved pressure gauge including a movable piston pressure sensing element and a gauge calibration element.
2. Description of the Prior Art
One embodiment of the present invention is designed to be similar in size and shape to truck tire gauge, to act as a replacement for it. The present invention generally utilizes a piston-type pressure element having a coil spring to provide a reactive force. Gauges of this general configuration are known in the prior art, and they are calibrated following assembly and before sale to the public. A problem with such prior art tire pressure gauges is that they can become inaccurate through usage, and it would be desirable to provide a mechanism for the user to accomplish a re-calibration of the gauge. Also, where the manufactured tire pressure gauge is calibrated at a manufacturer's selected calibration pressure, it is also desirable for the user to be able to re-calibrate the tire pressure gauge to obtain maximum accuracy at another user chosen pressure. The present invention provides a means for the user to re-calibrate a tire pressure gauge after it has been manufactured and calibrated by the manufacturer.